Hitherto, as a light-emitting device using an LED as a light-emitting element, there is a lamp device in which a board mounted with an LED is arranged in a housing, a lens unit is arranged over the board to face it, and surfaces of the housing and the lens unit are exposed to the outside.
The lens unit includes a lens part on which light generated by the light-emitting element is incident and which controls luminous intensity distribution, and is integrally formed of resin material or the like having transparency.
Although the surface of the lens unit is exposed to the outside, since the lens unit is formed of resin material, the thermal conductivity and heat dissipation are low as compared with metal or the like. Thus, sufficient heat dissipation for heat generated by the light-emitting element is not obtained from the lens unit side.